...which even my local CSA seems to manage. Not saying there isn't a burden, but it's nothing like laying fiber or laws which specifically ban direct sales of automobiles.
If there was big money to be made undercutting Big Potato, someone would do it. Even my CSA grows potatoes.
The OP asked for examples of things that prevent ethical companies from outcompeting unethical ones and I provided a few. Hyper-focusing on potatoes doesn't invalidate that.
Your local CSA is also unlikely to be audited by the FDA unless they tried to go larger than your community.
If there was big money to be made undercutting Big Potato, someone would do it. Even my CSA grows potatoes.